Mad Professor - Deep Blue Delay  [traced]

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Mad Professor - Deep Blue Delay

Postby neilnil » 04 Oct 2007, 11:04

I got this pedal months ago. Now I'm trying to trace it and posting gut shots first. I believe it's a variation of rebote delay with a PT2399. PCB is double-sided.

gut shot
solder side
pots

I will post about component values later.

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Last edited by neilnil on 04 Oct 2007, 16:02, edited 1 time in total.

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Postby The Rotagilla » 04 Oct 2007, 12:36

He's claiming up 600ms delay time. My experience with the PT2399 is that you star to get unwanted noise and digital hash when you exceed 300ms. Definitely curious about this one.
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Postby trevize » 04 Oct 2007, 13:45

But It could be a pt2399; two of the 4 harmony central review refer to a non functioning unit because of unwanted noise. It could be possibly just a pt2399 pushed too hard. Looks like a 350$ "rebote" delay ripoff or am I wrong.

Maybe the reviews are not objective and the pedal is really nice but a delay without a compander is not going to be silent...
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Postby neilnil » 04 Oct 2007, 15:55

gut shot with values

parts list
Capacitors:
100u
47u x3
1u x4

4.7n
2.2n x2
100n x4
47n
22n x2
15n
10n

100p
47p

Resistors:
1M
360k
180k
100k
22k
20k x2
12k
10k x7
5k
2.7k
2k
1k x2
33

ICs:
IC1
IC2
78L05

Diodes:
1N4xxx

What do you guys think about it? I want to trace the PCB but I'm afraid it would be quite hard for me since a lot of traces are made under the components.

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Postby nelson » 04 Oct 2007, 16:04

I wouldn't bother tracing it. With the 78L05 there it is probably a PT2399 based delay. Not worth the time and effort.
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Postby pz » 04 Oct 2007, 16:10

it definitely looks like pt2399 or its variation. Just take a look at the typ. application, pin2 goes to 47u (ref voltage filter), 3-4 - grounds, 100n near the pins 7,8. Second Ic is a dual opamp.
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Postby freedreamer » 05 Oct 2007, 13:32

very interesting this delay....
i would like to know more about it!
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Postby soggybag » 05 Oct 2007, 18:29

Sounds and looks very similar to the Rebote to me also.

I think the Rebote sounds pretty good. I'm not sure about exact time in ms but I get about 1/2 sec of clean delay. After that the sound starts getting very aliased very quickly.
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Postby markm » 05 Oct 2007, 20:14

:lol:

Love the defaced IC's!!
Join together with the "Banned"!
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Postby neilnil » 08 Oct 2007, 04:04

Just built a Rebote 2.5 but it won't sound as cool as DBD does. IMHO DBD has a really beautiful decay I love. Now I feel like tracing would be worth enough. OK see you soon.
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Postby bajaman » 08 Oct 2007, 05:23

I have built rebote delays and modded them extensively - a NE570 or NE571 makes quite a difference in my humble opinion - more later on - got to feed the dogs and go for my daily walk now :lol: :cry: :wink:
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Postby Eloy » 08 Oct 2007, 11:15

bajaman wrote:I have built rebote delays and modded them extensively - a NE570 or NE571 makes quite a difference in my humble opinion - more later on - got to feed the dogs and go for my daily walk now :lol: :cry: :wink:

Hi !
Can you point me to some info about that ?
I want to know learn how to use those in the RD2.5 .

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Postby bajaman » 08 Oct 2007, 11:40

Hi !
Can you point me to some info about that ?

Check out the Boss DM2 schematic or the Ibanez AD90 for starters
cheers
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Postby goaltoday » 08 Oct 2007, 12:32

PT2399 + NE570 = GGG PT-80.

Just tweak low pass filtering till you're satisfied.
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Postby markm » 08 Oct 2007, 15:34

neilnil wrote:Just built a Rebote 2.5 but it won't sound as cool as DBD does. IMHO DBD has a really beautiful decay I love. Now I feel like tracing would be worth enough. OK see you soon.
Jun


I'd be interested in any info you come up with.
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Postby osa » 11 Oct 2007, 15:44

markm wrote::lol:

Love the defaced IC's!!

That's not defacing.
That's "patent protection".
:roll: :roll: :roll:
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Postby neilnil » 12 Oct 2007, 15:09

Ok, here's my first attempt on its schematic.
Most differences from Rebote 2.0 are around lug 3 and 2 of repeat pot.
I can't read this schematic so please let me know what you think about it.
If there's a mistake I'll elaborate to fix it.
MP DBD Schematic 071012 - not verified yet
All pots are 50k linear, diode is 1N400x.
IC1 should be PT2399.
IC2 is a dual opamp and reads OP27x or OP27xx. Can you guess?
IC3 is 78L05.
Also check out its sound sample.
It has an interesting decay different from the way Rebote cuts highs.
sound samples

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Postby trevize » 12 Oct 2007, 15:11

I'm going to try the mods on an old rebote pcb I have at home. I stopped using it after building the pt-80 but now i have a good reason to work on it again!
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Postby The Rotagilla » 12 Oct 2007, 15:32

A quick glance looks like he's changed some of the filtering and extended the max delay time to 600ms. The app note for the PT2399 gives a max delay time of 342ms. I've done the 50k pot mod on the Rebote and once you get over 400ms the unwanted noise and digital hash renders the pedal useless for me. I've got a Rebote somewhere, I'll dig it out and play with the proposed changes as well.
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Postby bajaman » 12 Oct 2007, 20:47

The 2k and 47n strung from the delay level pot will attenuate the low frquency response of the repeats (high pass filter frequency is -3db at 1.7khz ), also the series resistance of the repeat pot at low repeat levels will roll off some extreme high frequencies too. The opamp is most likely an OP275.
Cheers
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PS: thanks Neilnil for sharing this info :D
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